The use of intravascular medical devices has become an effective method for treating many types of vascular disease. In general, a suitable intravascular device is inserted into the vascular system of the patient and navigated through the vasculature to a desired target site. Using this method, virtually any target site in the patient's vascular system may be accessed, including the coronary, cerebral, and peripheral vasculature.
Catheters are often utilized to place medical devices such as stents and embolic devices at a desired location within the body. A medical prosthesis, such as a stent for example, may be loaded onto a catheter in a configuration having a reduced diameter and then introduced into the lumen of a body vessel. Once delivered to a target location within the body, the stent may then be expanded to an enlarged configuration within the vessel to support and reinforce the vessel wall while maintaining the vessel in an open, unobstructed condition. The stent may be configured to be self-expanding, expanded by an internal radial force such as a balloon, or a combination of self-expanding and balloon expandable.
Balloon catheters are used in a number of endovascular applications including temporarily or permanently occluding blood flow either distal or proximal of a treatment site during neurological examinations, assisting in neurovascular embolic coiling of an aneurysm or arteriovenous malformations (AVM), and dilating narrowed blood vessels caused by vasospasm. Single lumen balloon catheters have a balloon disposed around a hollow balloon support member. The balloon is typically formed by an impermeable tube having its proximal end bonded (sealed) to the balloon support member and its distal end bonded (sealed) to the support member or to the catheter tip, with the support member forming a lumen through which a guidewire passes. A few inflation/deflation channels are either punched or laser drilled in the balloon support member to allow fluid communication between the catheter lumen, the balloon support member lumen, and the interior of the balloon. The inner diameter of the catheter lumen is narrowed at a location distal of the inflation/deflation channels so that a seal is formed by a guidewire passing through the lumen. In particular, the inner diameter of the sealing portion of the lumen is sized to form a close tolerance opening for passage of the guidewire while still allowing freedom of axial and radial motion of the guidewire. As such, these seals require the use of a specific guidewire with low outer diameter variability.
However, depending on the specific medical application, it may be desirable to use a variety of guidewires having different outer diameters with a same model balloon catheter. Further, manufacturing processes may result in high variability in guidewire outer diameters. There is a need for a balloon distal end seal configured to form a substantially fluid tight seal around a variety of guidewires having different outer diameters. An inadequate seal between the balloon distal end and the guidewire may lead to premature balloon deflation and may also result in blood entering the balloon. The entrance of blood into the balloon may further result in poor balloon visibility and clot formation around the inflation/deflation channels. Poor balloon visibility and inability to quickly deflate the balloon during a procedure could lead to vessel damage, tissue damage from prolonged anoxia, and other serious complications.